CVE-2026-45085: Discourse is an open-source discussion platform

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-45085 is a medium-severity flaw (CVSS 5.3) affecting discourse. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, four authorization/disclosure issues in the chat plugin (one also involving discourse-calendar): read-only category users could create chat threads, self-deleted chat messages could be restored by their author after channel access was revoked, moderators reviewing a flagged

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 89%)
CISA exploited list	No
Weakness	CWE-200, CWE-862
Published	2026-06-12
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: discourse

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-12 21:16 UTCPublished CVE record published
2026-06-17 18:46 UTCUpdated Record last modified

discourse discourse UPGRADE

Affected: < 2026.1.0 · >= 2026.1.0 and < 2026.1.4 · >= 2026.3.0 and < 2026.3.1 · >= 2026.4.0 and < 2026.4.1 · 2026.5.0

Fixed in: 2026.1.0, 2026.1.4, 2026.3.1, 2026.4.1

Safe to downgrade to: a release before 2026.1.0

1. Check installed version

apt-cache policy discourse || rpm -q discourse || discourse --version

2. UPGRADE to 2026.1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade discourse

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade discourse

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2026.1.0 (Debian / Ubuntu)

apt-cache madison discourse sudo apt install discourse=<VERSION_BEFORE_2026.1.0> sudo apt-mark hold discourse

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list discourse sudo dnf downgrade discourse-<VERSION_BEFORE_2026.1.0> sudo dnf versionlock add discourse

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-45085?

discourse: upgrade to 2026.1.0, 2026.1.4, 2026.3.1, 2026.4.1. Exact commands for each OS are on this page.

Is CVE-2026-45085 being exploited?

CVE-2026-45085 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-45085 affect?

CVE-2026-45085 affects discourse. Severity is medium (CVSS 5.3). Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, four authorization/disclosure issues in the chat plugin (one also

How urgent is CVE-2026-45085?

Priority 26/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-32244 MEDIUM 5.3 UPGRADE Discourse is an open-source discussion platform
CVE-2026-33514 MEDIUM 4.3 UPGRADE Discourse is an open-source discussion platform
CVE-2026-34154 MEDIUM 5.3 UPGRADE Discourse is an open-source discussion platform
CVE-2026-44780 MEDIUM 4.3 UPGRADE Discourse is an open-source discussion platform
CVE-2026-44782 MEDIUM 4.3 UPGRADE Discourse is an open-source discussion platform

References

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